1/*************************************************
2*      Perl-Compatible Regular Expressions       *
3*************************************************/
4
5/* PCRE is a library of functions to support regular expressions whose syntax
6and semantics are as close as possible to those of the Perl 5 language.
7
8                       Written by Philip Hazel
9           Copyright (c) 1997-2013 University of Cambridge
10
11-----------------------------------------------------------------------------
12Redistribution and use in source and binary forms, with or without
13modification, are permitted provided that the following conditions are met:
14
15    * Redistributions of source code must retain the above copyright notice,
16      this list of conditions and the following disclaimer.
17
18    * Redistributions in binary form must reproduce the above copyright
19      notice, this list of conditions and the following disclaimer in the
20      documentation and/or other materials provided with the distribution.
21
22    * Neither the name of the University of Cambridge nor the names of its
23      contributors may be used to endorse or promote products derived from
24      this software without specific prior written permission.
25
26THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
27AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
30LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36POSSIBILITY OF SUCH DAMAGE.
37-----------------------------------------------------------------------------
38*/
39
40
41/* This module contains an internal function for validating UTF-8 character
42strings. */
43
44
45#ifdef HAVE_CONFIG_H
46#include "config.h"
47#endif
48
49#include "pcre_internal.h"
50
51
52/*************************************************
53*         Validate a UTF-8 string                *
54*************************************************/
55
56/* This function is called (optionally) at the start of compile or match, to
57check that a supposed UTF-8 string is actually valid. The early check means
58that subsequent code can assume it is dealing with a valid string. The check
59can be turned off for maximum performance, but the consequences of supplying an
60invalid string are then undefined.
61
62Originally, this function checked according to RFC 2279, allowing for values in
63the range 0 to 0x7fffffff, up to 6 bytes long, but ensuring that they were in
64the canonical format. Once somebody had pointed out RFC 3629 to me (it
65obsoletes 2279), additional restrictions were applied. The values are now
66limited to be between 0 and 0x0010ffff, no more than 4 bytes long, and the
67subrange 0xd000 to 0xdfff is excluded. However, the format of 5-byte and 6-byte
68characters is still checked.
69
70From release 8.13 more information about the details of the error are passed
71back in the returned value:
72
73PCRE_UTF8_ERR0   No error
74PCRE_UTF8_ERR1   Missing 1 byte at the end of the string
75PCRE_UTF8_ERR2   Missing 2 bytes at the end of the string
76PCRE_UTF8_ERR3   Missing 3 bytes at the end of the string
77PCRE_UTF8_ERR4   Missing 4 bytes at the end of the string
78PCRE_UTF8_ERR5   Missing 5 bytes at the end of the string
79PCRE_UTF8_ERR6   2nd-byte's two top bits are not 0x80
80PCRE_UTF8_ERR7   3rd-byte's two top bits are not 0x80
81PCRE_UTF8_ERR8   4th-byte's two top bits are not 0x80
82PCRE_UTF8_ERR9   5th-byte's two top bits are not 0x80
83PCRE_UTF8_ERR10  6th-byte's two top bits are not 0x80
84PCRE_UTF8_ERR11  5-byte character is not permitted by RFC 3629
85PCRE_UTF8_ERR12  6-byte character is not permitted by RFC 3629
86PCRE_UTF8_ERR13  4-byte character with value > 0x10ffff is not permitted
87PCRE_UTF8_ERR14  3-byte character with value 0xd000-0xdfff is not permitted
88PCRE_UTF8_ERR15  Overlong 2-byte sequence
89PCRE_UTF8_ERR16  Overlong 3-byte sequence
90PCRE_UTF8_ERR17  Overlong 4-byte sequence
91PCRE_UTF8_ERR18  Overlong 5-byte sequence (won't ever occur)
92PCRE_UTF8_ERR19  Overlong 6-byte sequence (won't ever occur)
93PCRE_UTF8_ERR20  Isolated 0x80 byte (not within UTF-8 character)
94PCRE_UTF8_ERR21  Byte with the illegal value 0xfe or 0xff
95PCRE_UTF8_ERR22  Unused (was non-character)
96
97Arguments:
98  string       points to the string
99  length       length of string, or -1 if the string is zero-terminated
100  errp         pointer to an error position offset variable
101
102Returns:       = 0    if the string is a valid UTF-8 string
103               > 0    otherwise, setting the offset of the bad character
104*/
105
106int
107PRIV(valid_utf)(PCRE_PUCHAR string, int length, int *erroroffset)
108{
109#ifdef SUPPORT_UTF
110register PCRE_PUCHAR p;
111
112if (length < 0)
113  {
114  for (p = string; *p != 0; p++);
115  length = (int)(p - string);
116  }
117
118for (p = string; length-- > 0; p++)
119  {
120  register pcre_uchar ab, c, d;
121
122  c = *p;
123  if (c < 128) continue;                /* ASCII character */
124
125  if (c < 0xc0)                         /* Isolated 10xx xxxx byte */
126    {
127    *erroroffset = (int)(p - string);
128    return PCRE_UTF8_ERR20;
129    }
130
131  if (c >= 0xfe)                        /* Invalid 0xfe or 0xff bytes */
132    {
133    *erroroffset = (int)(p - string);
134    return PCRE_UTF8_ERR21;
135    }
136
137  ab = PRIV(utf8_table4)[c & 0x3f];     /* Number of additional bytes */
138  if (length < ab)
139    {
140    *erroroffset = (int)(p - string);          /* Missing bytes */
141    return ab - length;                 /* Codes ERR1 to ERR5 */
142    }
143  length -= ab;                         /* Length remaining */
144
145  /* Check top bits in the second byte */
146
147  if (((d = *(++p)) & 0xc0) != 0x80)
148    {
149    *erroroffset = (int)(p - string) - 1;
150    return PCRE_UTF8_ERR6;
151    }
152
153  /* For each length, check that the remaining bytes start with the 0x80 bit
154  set and not the 0x40 bit. Then check for an overlong sequence, and for the
155  excluded range 0xd800 to 0xdfff. */
156
157  switch (ab)
158    {
159    /* 2-byte character. No further bytes to check for 0x80. Check first byte
160    for for xx00 000x (overlong sequence). */
161
162    case 1: if ((c & 0x3e) == 0)
163      {
164      *erroroffset = (int)(p - string) - 1;
165      return PCRE_UTF8_ERR15;
166      }
167    break;
168
169    /* 3-byte character. Check third byte for 0x80. Then check first 2 bytes
170      for 1110 0000, xx0x xxxx (overlong sequence) or
171          1110 1101, 1010 xxxx (0xd800 - 0xdfff) */
172
173    case 2:
174    if ((*(++p) & 0xc0) != 0x80)     /* Third byte */
175      {
176      *erroroffset = (int)(p - string) - 2;
177      return PCRE_UTF8_ERR7;
178      }
179    if (c == 0xe0 && (d & 0x20) == 0)
180      {
181      *erroroffset = (int)(p - string) - 2;
182      return PCRE_UTF8_ERR16;
183      }
184    if (c == 0xed && d >= 0xa0)
185      {
186      *erroroffset = (int)(p - string) - 2;
187      return PCRE_UTF8_ERR14;
188      }
189    break;
190
191    /* 4-byte character. Check 3rd and 4th bytes for 0x80. Then check first 2
192       bytes for for 1111 0000, xx00 xxxx (overlong sequence), then check for a
193       character greater than 0x0010ffff (f4 8f bf bf) */
194
195    case 3:
196    if ((*(++p) & 0xc0) != 0x80)     /* Third byte */
197      {
198      *erroroffset = (int)(p - string) - 2;
199      return PCRE_UTF8_ERR7;
200      }
201    if ((*(++p) & 0xc0) != 0x80)     /* Fourth byte */
202      {
203      *erroroffset = (int)(p - string) - 3;
204      return PCRE_UTF8_ERR8;
205      }
206    if (c == 0xf0 && (d & 0x30) == 0)
207      {
208      *erroroffset = (int)(p - string) - 3;
209      return PCRE_UTF8_ERR17;
210      }
211    if (c > 0xf4 || (c == 0xf4 && d > 0x8f))
212      {
213      *erroroffset = (int)(p - string) - 3;
214      return PCRE_UTF8_ERR13;
215      }
216    break;
217
218    /* 5-byte and 6-byte characters are not allowed by RFC 3629, and will be
219    rejected by the length test below. However, we do the appropriate tests
220    here so that overlong sequences get diagnosed, and also in case there is
221    ever an option for handling these larger code points. */
222
223    /* 5-byte character. Check 3rd, 4th, and 5th bytes for 0x80. Then check for
224    1111 1000, xx00 0xxx */
225
226    case 4:
227    if ((*(++p) & 0xc0) != 0x80)     /* Third byte */
228      {
229      *erroroffset = (int)(p - string) - 2;
230      return PCRE_UTF8_ERR7;
231      }
232    if ((*(++p) & 0xc0) != 0x80)     /* Fourth byte */
233      {
234      *erroroffset = (int)(p - string) - 3;
235      return PCRE_UTF8_ERR8;
236      }
237    if ((*(++p) & 0xc0) != 0x80)     /* Fifth byte */
238      {
239      *erroroffset = (int)(p - string) - 4;
240      return PCRE_UTF8_ERR9;
241      }
242    if (c == 0xf8 && (d & 0x38) == 0)
243      {
244      *erroroffset = (int)(p - string) - 4;
245      return PCRE_UTF8_ERR18;
246      }
247    break;
248
249    /* 6-byte character. Check 3rd-6th bytes for 0x80. Then check for
250    1111 1100, xx00 00xx. */
251
252    case 5:
253    if ((*(++p) & 0xc0) != 0x80)     /* Third byte */
254      {
255      *erroroffset = (int)(p - string) - 2;
256      return PCRE_UTF8_ERR7;
257      }
258    if ((*(++p) & 0xc0) != 0x80)     /* Fourth byte */
259      {
260      *erroroffset = (int)(p - string) - 3;
261      return PCRE_UTF8_ERR8;
262      }
263    if ((*(++p) & 0xc0) != 0x80)     /* Fifth byte */
264      {
265      *erroroffset = (int)(p - string) - 4;
266      return PCRE_UTF8_ERR9;
267      }
268    if ((*(++p) & 0xc0) != 0x80)     /* Sixth byte */
269      {
270      *erroroffset = (int)(p - string) - 5;
271      return PCRE_UTF8_ERR10;
272      }
273    if (c == 0xfc && (d & 0x3c) == 0)
274      {
275      *erroroffset = (int)(p - string) - 5;
276      return PCRE_UTF8_ERR19;
277      }
278    break;
279    }
280
281  /* Character is valid under RFC 2279, but 4-byte and 5-byte characters are
282  excluded by RFC 3629. The pointer p is currently at the last byte of the
283  character. */
284
285  if (ab > 3)
286    {
287    *erroroffset = (int)(p - string) - ab;
288    return (ab == 4)? PCRE_UTF8_ERR11 : PCRE_UTF8_ERR12;
289    }
290  }
291
292#else  /* Not SUPPORT_UTF */
293(void)(string);  /* Keep picky compilers happy */
294(void)(length);
295(void)(erroroffset);
296#endif
297
298return PCRE_UTF8_ERR0;   /* This indicates success */
299}
300
301/* End of pcre_valid_utf8.c */
302